FAA Powerplant Written Practice Test

What purpose do counterweights serve on constant-speed propellers?

1. They stabilize the propeller during rotation.

2. They aid in decreasing the blade angle.

3. They facilitate increasing blade angle.

4. They help maintain a constant pitch angle.

The correct answer is: They facilitate increasing blade angle.

Counterweights on constant-speed propellers are primarily designed to assist in increasing the blade angle. In a constant-speed propeller system, the pilot or the propeller control unit adjusts the blade angle to maintain a specific engine speed, even when the power output is varied. As the engine power increases, the centrifugal force acting on the blades also increases, which might cause the blades to tend toward a flatter angle. The counterweights help to counteract this effect by providing a force that tends to increase the blade angle, ensuring that the blades can adjust to maintain the desired RPM. This action is critical during power changes, especially during climbs or when rapid acceleration is required. In summary, counterweights play a vital role in the dynamic adjustments of the propeller, aligning the blade angle with the demands of the engine speed and load, thus helping the system achieve optimal performance.